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Old 07-09-2003, 02:26 PM
Registered User
Join Date: Oct 2001
Location: Seattle Area
Posts: 373
M119 - oily spark plugs

Ok guys, wierd one here (or wierd to me at least). Hopefully it isn't as scary as it looked.

Tuning up the E420 that just went over 60k last week. Putting in new Caps, Rotors, Plugs, filters, etc....when pulling the spark plugs, almost half came out covered in oil right around the threads. I mean like, dripping, black oil. The tips of the plugs themselves looked fine - nice grey dust, no corrosion or indication that oil was being burned. What could this be?

The valve cover gaskets are weeping, is that somehow leaking down into the plug holes? The car runs fantastic - not a hint of smoke or oily fact just got 26 mpg on a recent road-trip BEFORE the tune-up. I guess I can see some oil finding it's way down there if you sloshed oil out while filling, but I found this condition on both the right and left side of the engine.

Any ideas?

- Ryan, scared in Seattle
'95 E420 - 'Shadowfax' 138kmi.
'92 Volvo 740Turbo Bard 193kmi
'74 240D - 'Ol' Green' 4spd Manual 104kmi. (sold )
'77 300D - 'Red' 223kmi (sold)
'75 240D - 'Bianca the Blue Bomber' (sold)
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Old 07-09-2003, 04:57 PM
DR.DIESEL's Avatar
Senior Member
Join Date: Mar 2003
Location: Puget Sound, Washington St.
Posts: 522
The 4 seal rings in the valve cover that seal the plug hole chambers could be seaping oil down into the plug hole.
Once there, the oil works it's way down the plug threads.
It does a pretty good job of keeping the threads lubed!
I would start with a new set of v/c gaskets. Don't forget to replace the copper crush seals for each v/c bolt as well.
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